// 单纯用于撑开零高容器, 让零高容器放置的交互内容可见
// 不放任何内容
// surface-height(1, 2)
// surface-height({width, height})
mixin surface-height(...args)
  -var contentWidth = 0
  -var contentHeight = 0

  if typeof args[0] === 'object'
    -contentWidth = args[0].width
    -contentHeight = args[0].height
  else 
    -contentWidth = images[0].width
    for idx in args
      -contentHeight += images[idx].height

  section(style="line-height:0;display: block;pointer-events:none;")
    svg(style="max-width:none!important;pointer-events: none;", viewBox=`0 0 ${contentWidth} ${contentHeight}`, xmlns="http://www.w3.org/2000/svg", xmlns:xlink="http://www.w3.org/1999/xlink")
    block
